But in all those frequent caera talks, nobody ever asks me about sensor size...

So In those casual talks you have, do the others ask you about sensor size or does it become a subject only after you bring it up?

It is always about the lenses. Like which is better macro lens, how the output from fast Sigma lenses differ from the output from fast Zeiss lenses, is Canon 24-70/2.8 better than the Nikon one, etc. It's understood the larger sensor will deliver more than the smaller one.

I was just wondering about your initial question, which was the following:

"Let's say you are somewhere in the street or in the park, and someone mentions you have a small camera with the smallish sensor in it, you show them the pictures - how?"

Indeed, sensors and their size never get discussed in real life. Only here.

Megapixels, yes, sometimes, and most often for the wrong reasons (how many MP on the microscopically small sensor of my phone cam or compact). But sensors never, except in internet forums and camera stores, where people push gear that is most convenient and "harmless" to push.